Process for simultaneously producing phosphoric acid and silicon alloys



Patented May 7, 1935 UNITED STATES PROCESS FOR S IMULTANEOUSLY PRODUC- ING PHOSPHORIC ALLors Marvin J. Udy, Anniston,

Research, Alabama ACID AND SILICON Ala., assignor to Swann Incorporated, a corporation of No Drawing. Application April 28, 1932,

Serial No.

1 Claim.

This invention relates to a process for simultaneously producing phosphorus and silicon alloys.

One object of this invention is the provision of a process for the'productio'n of silicon alloys such as silicon-iron, silicon manganese, silicon-vanadium, silicon-tungsten, silicon-molybdenum or combination alloys, such as iron-silicon-manganese in an electric furnace such as is at present used for the production of phosphorus or phosphoric acid.

It is already known that ierro-phosphorus can be produced in an electric furnace by smelting a burden of phosphatic ore, carbon and a siliceous flux, together with iron or iron ore.

I have now made the discovery that if the proportion of siliceous flux and carbon be increased above that usually employed in phosphate smelting, a considerable amount of the silicon present can be reduced to the elemental state and combined with a metal such as iron, manganese, vanadium, tungsten, molybdenum, which has been added to the charge. The silicon alloy thus produced is low in phosphorus and can be tapped from the furnace in the same manner as ferrophosphorus and constitutes a valuable product.

Such a procedure as above described is of particular benefit when it is desired to obtain greater yields of phosphorus or phosphoric acid from the smelting operation. In addition to thus obtaining greater yields I have also found that the addition of metals or metallic ores to the smelting burden results in a smoother operation of the furnace and also results in the furnace producing a purer form of phosphoric acid. This latter effect, I believe, to be due to the strong alloying tendency between silicon and the metals mentioned, thus preventing the silicon from being vaporized and carried out with the phosphorus vapor,

My discovery may be applied to the production of silicon containing alloys of the type already mentioned by properly proportioning the burden. When supplying the silicon alloying ingredientof the burden, I prefer to add either an oxide or an ore of the metal or the metal itself, if available. Thus when producing a silicon-iron alloy I supply the iron either in the metallic form as iron scrap or as iron-ore with the requisite amount of carbonaceous matter for reduction. When producing a manganese silicon alloy I supply the manganese as a manganese ore together with carbonaceous matter for reduction, or as ferro-manganese. In a similar manner I may add to the charge a vanadium ore together with carbonaceous matter or ferro-vanadium. When producing silicon-tungsten alloys I may utilize ferberite or sheelite in the burden to supply this element. In all cases it is desirable that the silicon in the stud be at as high as 48%, in

which case the phosphorus in the alloy will beat a minimum.

In carrying out the process of the present invention, the following examples are suggested as illustrative only, the invention being limited only asindicated bythe prior art or as particularly pointed out in the appended claim: 1

Example 1 The following burden is provided:

' I 1 Pounds Phosphate rock 13.4% P 3,000 Silica rock 95% S102 1,475 Coke 70% fixed carbon; 1,120 Iron scrap 422' silic a lime is formed during this operation.

Example 2 A burden of the following type is provided:

v 7 Pounds Phosphate rock 13.4% P 3,000 Manganese ore: (Mn 19%, Fe 30%, SiOz 18%) 1, 000 Silica rock 95% Si 1, 524 Coke 70% fixed carbon 1, 533

This burden is smelted in an electric furnace in the same manner as above, phosphorus being recovered. from the gases to the extent of 95 to 97% of that present in the burden. The silicon alloy recovered is approximately of the composition: Fe=30%; Mn=19%; Si=50% and phosphorus less than 0.4%.

A slag having the ratio silica lime is formed during this operation.

Example 3 If a high grade manganese ore is available a substantially higher grade manganese-silicon alloids to the elemental state.

metalloidsare those which it is desired to alloy:.

loy may be produced. The following burden is employed:

Pounds Phosphate rock 13.4% P 3, 000 Manganese ore: (Mn 55%; FezO .2.0%;

SiOz 8.0% 1,000 Silica rock 95% SiOz 1, 813 Coke 70% fixed carbon 2, 354

This burden is smelted in an electric furnace silica V lime is formed during this operation.

In a manner analogous to that illustrated above I may'produce vanadium-silicon alloys;

tungsten-silicon alloys, or molybdenum-silicon alloys as cor-products of the phosphorus smelting operation. The principles of burdening are those employed above and arebriefiy as follows:

Sufficient carbon is employed in the burden to reduce, the phosphate and the metals or metal- The metals or i.- e., iron, ,silicon, manganese, vanadium, tungsten, molybdenum. Sufficient silica is employed to fin'nish the silicon in the alloy together with that necessary to slag the bases in the burden, i. e., the lime, magnesia, alumina, etc. More than 40% of silicon in the alloy is desirable and in most cases at least 48 to 50% is necessary to reduce the phosphorus content below 0.4%. The slag which is produced may be of varying composition, the composition suggested is merely illustrative. As far as I am aware, the slag performs no'refining function in the furnace, it is calculated to be of free-running composition in accordance with accepted and well-known principles.

While I have described only a few embodiments of my invention, it will be apparent to those skilled in the art that it is not so limited, but that it is susceptible of various changes and modifications without departing from the spirit thereof, and I desire that only such limitations shall be placed thereupon as maybe imposed by the prior art, or as are specifically set forth in the appended claim.

I claim:

The process which consists in smelting 'a calcium containing phosphatic ore, a manganese ore and silica together with sufficient carbonaceous material to reduce both said phosphatic ore and said manganese ore and a part of said silica to silicon, whereby a manganese-silicon alloy is formed from said reduced portion of said silica, and combining said unreduced silica with the calcium contained in the phosphatic ore to produce therewith a'fusible slag, and simultaneously recovering phosphorus therefrom.

MARVIN J. UDY. 

